Low Complexity Iterative Rake Detector for Orthogonal Time Frequency Space Modulation

Thaj, Tharaj; Viterbo, Emanuele

doi:10.1109/wcnc45663.2020.9120526

Cited by 52 publications

(26 citation statements)

References 12 publications

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“…For the rest of the paper, to differentiate with the basic OTFS scheme, as discussed in [1], [9], we refer to the above scheme including zero padding as the ZP-OTFS. Our main motivation behind adding the delay-Doppler domain ZP is the design of a low complexity detector for OTFS, [3]. Adding a ZP along the delay dimension in the OTFS delay-Doppler grid can be seen as analogous to the time-domain CP or ZP added in orthogonal frequency division multiplexing (OFDM), which allows the design of a single tap equalizer in the time-frequency domain, and hence contribute to reduction in detector complexity.…”

Section: ) Basic Otfs Transmitter and Receivermentioning

confidence: 99%

“…Remark -The above three cases result in phase changes ( − ) due to the rectangular pulse shaping waveforms. For the ideal pulse shaping waveform assumption, it was shown in [3], [9] that the Doppler spread vectors…”

Section: E Input-output Relations In Delay-doppler Domainmentioning

confidence: 99%

“…As a result, a time-frequency selective channel due to multipath fading and mobility, is converted into a separable and quasi-orthogonal interaction, where all received information symbols experience roughly the same localized impairment [1]. Hence, for each A preliminary version of this work will be presented in part at the IEEE Wireless Communications and Networking Conference (WCNC), May 2020, [3]. The authors are with Department of Electrical and Computer Systems Engineering, Monash University, Clayton, VIC 3800, Australia.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we propose an iterative rake receiver for the OTFS system using the maximal ratio combining scheme. Following [3], we group the delay-Doppler grid symbols into vectors according to their delay index and reformulate the input-output relation between the transmitted and received frames in terms of these transmitted and received vectors. By placing some null symbols (zero-padding (ZP)) in the delay-Doppler domain we arrive at a reduced input-output relation, which allows the use of the maximal ratio combining to design a low complexity detector for OTFS.…”

Section: Introductionmentioning

confidence: 99%

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Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

Thaj¹,

Viterbo²

2021

Preprint

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<div>This paper presents a linear complexity iterative rake detector for the recently proposed orthogonal time frequency space (OTFS) modulation scheme. The basic idea is to extract and coherently combine the received multipath components of the transmitted symbols in the delay-Doppler grid using maximal ratio combining (MRC) to improve the SNR of the combined signal. We reformulate the OTFS input-output relation in simple vector form by placing guard null symbols or zero padding (ZP) in the delay-Doppler grid and exploiting the resulting circulant property of the blocks of the channel matrix. Using this vector input-output relation we propose a low complexity iterative decision feedback equalizer (DFE) based on MRC. The performance and complexity of the proposed detector favorably compares with the state of the art message passing detector. An alternative time domain MRC based detector is also proposed for even faster detection. We further propose a Gauss-Seidel based over-relaxation parameter in the rake detector to improve the performance and the convergence speed of the iterative detection. We also show how the MRC detector can be combined with outer error-correcting codes to operate as a turbo DFE scheme to further improve the error performance. </div><div>All results are compared with a baseline orthogonal frequency division multiplexing (OFDM) scheme employing a single tap minimum mean square error (MMSE) equalizer.</div>

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Section: ) Basic Otfs Transmitter and Receivermentioning

confidence: 99%

Section: E Input-output Relations In Delay-doppler Domainmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

Thaj¹,

Viterbo²

2021

Preprint

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“…In the recent few years, there has been a number of efforts dedicated to the development of OTFS (e.g. [5]- [21] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

Thaj¹,

Viterbo²,

Hong³

2021

Preprint

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This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

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2024

OTFS Modulation ‐ Theory and Applications

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Low Complexity Iterative Rake Detector for Orthogonal Time Frequency Space Modulation

Cited by 52 publications

References 12 publications

Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

Low Complexity Iterative Rake Decision Feedback Equalizer for Zero-Padded OTFS systems

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

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